New Cam and Rockers - odd looking at 500+ miles

[inline6]

The new engine has something like 500 miles on it.  So, I took off the valve cover to inspect everything, and adjust valve lash.  Really surprised by what I am seeing here.  Something is wrong, but maybe it is minor.  

 

It appears to me that the rocker pads are depositing material onto the lobes of the cam.  Take a look at the pics.

 

Lobe #12

 

Lobe #10

 

Lobe #5

 

I think the silvery stuff is coming from the rocker pad.  When I run my fingernail over it, it has a noticeably rough texture.  

 

Here is the number 10 rocker from different angles:

 

 

 

 

 

There is visible wear on the contact surface (though slight) on the "opening" side.  As you can see by the profile view, it is not very much.  I took pics at just the right lighting so you can see the wear edge.

 

So, why has this happened?  

 

• I know the rocker geometry is right - the wear patterns were checked during assembly and they are looking good now also.  
• The camshaft has been nitrided... could it be that the hardened/nitrided surface is causing this?
• On first engine start, I ran the engine for 20 minutes at 2000 RPM for "break in" even though with a nitrided cam, I don't think it was necessary.

 

 

 

 

[skirkland1980]

I'd say the rockers are too soft. Are they new or resurfaced?

[inline6]

I'd say the rockers are too soft. Are they new or resurfaced?

 

They are new OEM... at least, they came in Nissan boxes, and wrappers... off of eBay.  Any way to tell by looking at them?

 

Oh, and the cam is internally drilled... and I have a good functioning, stock oil spray bar.  Shouldn't be any issues running with both from what I researched...  but now I am wondering if there isn't enough lubrication.  

 

On my 510, I couldn't run more than 460 lift without adding an external spray bar.  Is it possible, that with internal drilling and the spray bar that this high lift cam is not getting enough oil on the lobes?  The problem is on all cam lobes...

Edited April 3, 2013 by inline6

[brianZortiz]

I have this problem with a regrind cam and resurfaced rocker arms. I'm at 250 miles on build, but only 2 lobes have this scuffing. Hope someone here chimes in to hopefully fix the problem. 

[BlueStag]

 but now I am wondering if there isn't enough lubrication.  

 

On my 510, I couldn't run more than 460 lift without adding an external spray bar.  Is it possible, that with internal drilling and the spray bar that this high lift cam is not getting enough oil on the lobes?  The problem is on all cam lobes...

 

I can see no disadvantage to adding a spray bar, even if the cam were getting enough lube without it.

[NewZed]

WAG on inline's problem - coil bind on the springs?  Maybe after everything gets hot.  Can't really tell from the straight-on picture angle but it looks like the wear is happening evenly before and after maximum lift, when you'd think that it would happen where the ramp starts and on the way up.

[inline6]

WAG on inline's problem - coil bind on the springs?  Maybe after everything gets hot.  Can't really tell from the straight-on picture angle but it looks like the wear is happening evenly before and after maximum lift, when you'd think that it would happen where the ramp starts and on the way up.

 

Took me a minute - Wild Ass Guess...  

 

I pulled my documentation from the build.  These springs are custom spec'd for the cam.  Here are the specs:

 

7700 RPM max - One spring only on intake and exhaust

 

Intake:

Installed at 1.680" with 54 lbf.

Open height = 1.130" or .550" lift with 193 lbf.

 

Exhaust:

Installed at 1.680" with 54 lbf.

Open height = 1.130" or .550" lift with 193 lbf.

 

Actual build notes:

Springs - 1.700" - 1.705" = 58 lbf in valve spring checker

 

Seat: 1.710" = 56 lbf

Open: 1.160" = 190 lbf (.550" lift)

 

.578" to coil bind - minimum

 

So, is that difference .578" vs. .550" ok, or tight?  Valves are Manley stainless, retainers are titanium.

Edited April 3, 2013 by inline6

[NewZed]

I haven't built any engines in real life, only in my head.  I just threw that out as something that might match the evidence, a brainstorming thing.  I could be way off.  Since everything is installed, it would be easy to measure how much room is left in the springs at maximum lift.  Valve lash generally gets looser when hot, but it's hard to imagine what the springs and valves might do.  You might find you have tons of room and can think about some other potential cause.

 

It might be something as simple as poor heat treating on the rocker arm pads.

[Xnke]

Wrong engine oil and improper metallurgy. The nitrided cam is now too hard for the rocker arms, and the lack of EP additives in the oil are allowing metal to metal contact. Since the rockers are softer, they are taking the most damage from the microwelding that occurs from the lack of oiling.

[NewZed]

It would be good to see all of the details on both setups.  Cam grinder, shaft material, nitriding on just one or both, break-in lube, oil used for the first 500 miles, ZDDP, etc.  From what I see about nitriding, it's supposed to reduce galling.  Metal to metal contact is always bad so maybe it's just oil quantity.  I didn't see anything about oil type in the previous posts.

 

Maybe the nitrided surface needs polishing before use to be effective, since it's too hard to wear in.  I seem to recall that the process leaves a rough surface behind.

 

Interesting problem. 

 

Edit - the nitriding process would good to know also, since there are several.

Edited April 3, 2013 by NewZed

[inline6]

Wrong engine oil and improper metallurgy. The nitrided cam is now too hard for the rocker arms, and the lack of EP additives in the oil are allowing metal to metal contact. Since the rockers are softer, they are taking the most damage from the microwelding that occurs from the lack of oiling.

 

Oil is Mobil 1 - the full synthetic 10W30 stuff.  I would have thought Jim Thompson from Kinetic Motorsports would have raised a concern with regard to getting the camshaft nitrided.  I just now sent a note via their contact form asking about the issue, and will see how that goes.

 

 

It would be good to see all of the details on both setups.  Cam grinder, shaft material, nitriding on just one or both, break-in lube, oil used for the first 500 miles, ZDDP, etc.  From what I see about nitriding, it's supposed to reduce galling.  Metal to metal contact is always bad so maybe it's just oil quantity.  I didn't see anything about oil type in the previous posts.

 

Maybe the nitrided surface needs polishing before use to be effective, since it's too hard to wear in.  I seem to recall that the process leaves a rough surface behind.

 

 

I tracked down some of my emails with Kinetic where we discussed the nitriding...  Here are some excerpts:

 

"The cam blanks used by our cam grinder have never been "CWC" blanks.  Though Kinetic has tried Nitriding and Parkerizing in the past, the fine polish finish on the lobes has worked best for lobe durability.  I asked Jim to confirm the cam grinder used the same cam blank (Estas) as usual."

 

And from the same email thread:

 

"That said, as it stands now, I would feel more comfortable with a Nitride treatment, but I don't want to ruin the fine finish on the lobes if that is beneficial.  You guys are the experts, just tell me which way I should go.  The couple week turn around won't be a problem for me

because the car is down for the winter.

 

How should we proceed?"

 

 

So summarizing:

Cam grinder: Kinetic Sunbelt (actually subcontracted)

Shaft material - don't know for sure, but cams used by Kinetic Motorsports (cam blank is Estas)

Nitriding done on cam only - I am not sure of the type - totally guessing it is ion nitride instead of ammonia gas for less warping

No break in lube - just assembly lube - and I can get that info if needed.

Oil used - Mobile 1 full synthetic 10W-30

No ZDDP or any other additives.

Edited April 5, 2013 by inline6

[EvilC]

I am near 500 miles on my build also and will be pulling the valve cover too. Interesting to see how the metal has worn in that short time. If you are going to run the spray bar - I have been told to run the turbo oil pump. I am doing this currently so will report back to you maybe this weekend.

[Tennesseejed]

inline6, sorry to hear you are having some issues with your 3.1 build.  Your engine build thread is a goldmine of information. 

 

Couple of thoughts that may not be worth anything:

 

1.  You say that the rocker wipe pattern is good - and holding the rocker in person is certainly better than viewing a small picture - but the first picture of rocker #10 appears to show the lobe contacting the rocker off the edge of the pad.  In any event, your lobes are clearly picking material off of your rockers. 

 

2.  I know that you consulted many professionals in your build, and Lord knows they know more than I do, but an installed spring pressure of 54# for a high revving engine seems awfully light.  As engine revolution increases, and the combustion event timing shortens, you generally need more spring pressure to keep your valves from floating.  Perhaps your ultra light titanium valves (and valve train components?) permit such a light spring pressure, but I would expect to have a closed seat pressure in the neighborhood of 154# and up to 290# open (~100# more than your springs) for a +7000K redline engine. 

 

Just my .02.  Hope you find a simple and inexpensive solution.

[Lazeum]

have you checked valve clearance?

It seems I'd got the same exact issue except I found it when cam lobe & rockers were so worn that one rocker came out lose & get broken into pieces in my head.

 

I had driven the car for 200 mi max before it happened after new head made by Braap was installed on my L28 short block.

We've suspected oil starvation but after engine tear-down, I haven't noticed anything blocked.

 

I've contacted Rebello who was the cam grinder, he said issue had nothing to do with cam or rocker, only lube issue.

I've also checked part geometry. I was working in auto industry. I had access to state of the art equipment to measure anything as low as a tenth of micrometer. Everything was very straight.

 

So a 5-why analysis allowed me to come up to the following conclusion:

Lack of lube => heat => metal tempering => hardness down => wear => failure

 

Since, I've rebuilt my engine; crankshaft needed regrind, piston clearance was bad, block had metal chips in every gallery, oil pump was shot.

Head was sent back to Paul (see where I live!?), cam was changed with a brand new reground core, rockers were replaced with new ones, wipe pattern was fully checked, lube system was upgraded with spray bar.

 

Have you also noticed any black spots on rockers? looking at my rockers, they were black on the tip which is a clear sign of a lot of heat generation.

 

 

 

New engine has now 700 mi & it seems valve clearance is the culprit on my side. At failure time, I've noticed 0 clearance and I've experienced it also on my new engine. Since I was checking valve clearance every 50 mi (talk about being paranoid!) on new engine, I've taken care of it. Valve clearance is now almost stabilized but I'm still checking every 100-150 mi.

So I believe the lack of lube being caused by no clearance (=permanent friction) had been the root cause for heat on my side.

See my thread about it.

 

no valve clearance => Lack of lube => heat => metal tempering => hardness getting down => wear => failure

 

also, 0 valve clearance = no time for valves to cool down against seats => burnt valves => failure

 

I've got tons of pictures in my archives, if you'd like to get some more, just shoot me an IM and I'll send you some if that could help.

Edited April 4, 2013 by Lazeum

[clarkspeed]

All good ideas from above. Hope you can drive this to root cause. I've never seen this and I have torn up a few cam/rockers in the past. After my last build , I found 2 of the spray bar holes were clogged (cam not drilled). I ran 2 hours on track before it was discovered. Some cam discoloration and light scoring but no damage. There is a lot of oil sloshing around up there.With those light valve springs I would think you have more margin before damage. I always coat the cam with high zinc assembly lube and use a zinc additive in petroleum based oil on breakin. High zinc synthetic thereafter.

[Tony D]

"Have you also noticed any black spots on rockers? looking at my rockers, they were black on the tip which is a clear sign of a lot of heat generation."

 

That color is from serious heat generation. I would also address oil flow and monitor temperatures in the region!

 

Tracing it to valve recession is something that you should have caught during routine breakin-checks (every 100KM would be my guess...not more 200 km up to the first 1000km.)

[madkaw]

They are new OEM... at least, they came in Nissan boxes, and wrappers... off of eBay.  Any way to tell by looking at them?

 

Oh, and the cam is internally drilled... and I have a good functioning, stock oil spray bar.  Shouldn't be any issues running with both from what I researched...  but now I am wondering if there isn't enough lubrication.  

 

On my 510, I couldn't run more than 460 lift without adding an external spray bar.  Is it possible, that with internal drilling and the spray bar that this high lift cam is not getting enough oil on the lobes?  The problem is on all cam lobes...

 

I don't know if this has anything to do with this situation or not, but I did an extensive experiment with the "dual" lubrication method for the cam. I was driving my oil pump with a heavy duty drill and actually watched the results of the internally oiled cam and the spray bar combo. The oil from the spray bar didn't even reach the cam followers, and this was with a heavy duty pump with heavier pump spring. There was still decent pressure coming out of the cam holes, I believe enough to lubricate the cam, but the spray bar was doing no good. To me, it was just more things to go wrong and i eliminated the spray bar. I think the internally oiled cam is WAY more than enough lubrication for the cam-especiallly if you see how it sprays out those holes.

There is a thread on Classic Z somewhere that i started, but I'm to lazy to look it up.

Hope you find your issue, I have enjoyed watching your build 

[PMC raceengines]

Sorry to say this but that happend about 3 minets after you started the engine , i have seen it so many times on the engine dyno , heat from oil problem did it , and there is only one fix remove and replace rockers and cam start again , i have seen a cam do it on the bench before it was started because it was dry and was picking up when turned over setting up  the rockers .

[inline6]

Sorry to say this but that happend about 3 minets after you started the engine , i have seen it so many times on the engine dyno , heat from oil problem did it , and there is only one fix remove and replace rockers and cam start again , i have seen a cam do it on the bench before it was started because it was dry and was picking up when turned over setting up  the rockers .

 

For clarity, were you saying this about my cam and rockers or about Lazeum's?  I think my cam and rockers are still quite useable though they need some attention.

 

Also, can you explain this part some more, as seeing "a cam do it on the bench before it was started" sounds very interesting.  What is "it" and can you explain "and was picking up when turned over setting up the rockers."  Picking up what?  If you are referring to my pictures and not Lazeums, please let me know.  

Edited April 5, 2013 by inline6

[inline6]

have you checked valve clearance?

 

Have you also noticed any black spots on rockers? looking at my rockers, they were black on the tip which is a clear sign of a lot of heat generation.

 

Before I removed the one rocker I took a picture of, I checked the valve clearance on a few...  3 to be exact.  .25 mm and .30 mm were the feeler gauge sizes. I forget which is for intake and which is for exhaust, but I was just doing a quick check.  Two of the clearances I checked were intakes and one was exhaust.  The .30 mm fit in one only.  The other two accepted the .25 mm gauge.  So, seeing the clearances were close, I obviously moved on rather quickly to pulling one of the rockers for examination.  No dark areas on my rockers.  Heat like you experienced did not occur with this engine.  

 

Sorry to hear you have had such major problems.  I know that has been difficult to deal with after hoping for a nice experience from the new engine.

 

All good ideas from above. Hope you can drive this to root cause. I've never seen this and I have torn up a few cam/rockers in the past. After my last build , I found 2 of the spray bar holes were clogged (cam not drilled). I ran 2 hours on track before it was discovered. Some cam discoloration and light scoring but no damage. There is a lot of oil sloshing around up there.With those light valve springs I would think you have more margin before damage. I always coat the cam with high zinc assembly lube and use a zinc additive in petroleum based oil on breakin. High zinc synthetic thereafter.

 

I had come across the posts about zinc before in the forums, but since my stock cam and valve train (old engine) had been rebuilt in the 90's and run for many ten thousands of miles over the years with absolutely no issues, I really didn't feel the need to invest a lot of time reading about it.  Definitely more interested now...  My engine builder is pretty top notch, and I know he used cam lube.  I just haven't bothered calling him to see which.  I found an assembly pic that shows the cam lube...

 

 

I don't know if this has anything to do with this situation or not, but I did an extensive experiment with the "dual" lubrication method for the cam. I was driving my oil pump with a heavy duty drill and actually watched the results of the internally oiled cam and the spray bar combo. The oil from the spray bar didn't even reach the cam followers, and this was with a heavy duty pump with heavier pump spring. There was still decent pressure coming out of the cam holes, I believe enough to lubricate the cam, but the spray bar was doing no good. To me, it was just more things to go wrong and i eliminated the spray bar. I think the internally oiled cam is WAY more than enough lubrication for the cam-especiallly if you see how it sprays out those holes.

There is a thread on Classic Z somewhere that i started, but I'm to lazy to look it up.

Hope you find your issue, I have enjoyed watching your build 

 

Thanks... I am running a "high capacity" pump which is most likely a 280ZXT pump.  I bought it from Malvern Racing - (Datsun Competition dealer) back in the 90's, and ran in my 4 cyl. 510 motor for a long time.  For this engine build, we took it apart and modded it a bit for improved flow.  Instead of running the high pressure spring, I run with the standard spring and a washer (used as a shim to bump the pressure up just a tad).  I'll definitely need to check the spray bar for flow issues.  Since all the lobes are looking very consistent with regard to the amount of deposits on them, it would seem my problem is also very consistent.  I'll also need to check oil pressure across the engine operation spectrum.  Perhaps I don't have enough pressure for 7700 RPM.  I don't think that is a problem, but it I have not checked it.  The rule of thumb is what 10 psi per 1000 RPM?

Edited April 5, 2013 by inline6